Water and wastewater treatment facilities are often among the largest consumers of electricity for a city or municipality. As such, there is a significant focus on improving these facilities’ efficiency and reducing electricity usage. In this blog, OnSite Partners dives into the intersection of engineering, data analytics, and electricity bill dynamics to explore how water facilities can achieve substantial cost savings.
Understanding Variable Frequency Drives (VFDs)
Variable Frequency Drives (VFDs) are used to control the speed of equipment like centrifugal blowers and pumps. Unlike systems that operate solely in an on-or-off mode, VFDs allow for variable production, providing significant control over operations. This variability is governed by the Affinity Laws, which describe the relationships between speed, flow, pressure, and power consumption:
- Flow: Has a linear relationship to speed. Reducing speed to 50% results in 50% of the flow.
- Pressure: Has a square relationship to speed. At 50% speed, the pressure differential drops to 25%.
- Power Consumption: Has a cubic relationship to speed. At 50% speed, power consumption is only 12.5% (1/8) of the maximum.
This non-linear relationship underscores the potential for massive energy savings when VFDs are implemented strategically.
Electricity Bill Dynamics and Their Impact
Water facilities’ electricity bills are influenced by several components, which VFDs can help manage effectively. Three key factors to consider are:
- Load Factor: This metric compares a facility’s peak power consumption to its average power use. A high load factor indicates significant variability in consumption, which often results in higher charges. Facilities can save by maintaining a load factor as close to one as possible, signaling consistent energy use.
- Peak Load Contribution (PLC): Many electricity providers calculate a portion of a facility’s bill based on its contribution to the zone’s peak load. In some cases, PLC charges can comprise up to 40% of a facility’s electricity costs. Reducing consumption during peak load periods can yield substantial savings.
- Demand Response Programs: Regional Transmission Organizations (RTOs) oversee the balance of supply and demand across the grid. They offer incentives to facilities that can reduce electricity usage during periods of grid stress. Facilities participating in demand response programs can benefit financially while contributing to grid stability.
Optimizing Facility Operations with VFDs
To maximize savings, facilities must assess their infrastructure and operational patterns. Reservoirs, tanks, and historical usage data can offer insights into energy-saving opportunities:
- Reservoir Management: Reservoirs allow for strategic shifting of flows and electricity usage. For instance, if a zonal peak is anticipated in the late afternoon, a facility could fill reservoirs earlier in the day, enabling pumps to run at lower capacities during peak times.
- Dynamic Scheduling: By aligning pump and blower operations with non-peak periods, facilities can reduce their Peak Load Contribution and lower their overall electricity costs.
Leveraging Technology for Greater Efficiency
Modern control systems that integrate VFDs, data analytics, and artificial intelligence (AI) provide powerful tools for optimizing facility performance. These systems can:
- Predict peak load periods and adjust operations accordingly.
- Automate energy-efficient operation schedules.
- Monitor real-time performance and identify inefficiencies.
Moreover, solutions can be implemented with no up-front capital expenditure. Innovative financing options, such as performance-based contracts, enable facilities to fund upgrades through the savings they generate on electricity bills.
Conclusion
By understanding the interplay between VFDs, the Affinity Laws, and electricity bill dynamics, water facilities can unlock significant cost-saving opportunities. With careful analysis of facility operations and the adoption of advanced technologies, municipalities can reduce energy consumption, improve grid reliability, and achieve long-term financial benefits. Whether it’s through optimized reservoir usage or participation in demand response programs, the potential for smarter, more efficient water facility operations is immense.